/*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.facebook.presto.operator.aggregation;
import com.facebook.presto.spi.block.Block;
import com.facebook.presto.spi.block.BlockBuilder;
import com.facebook.presto.spi.block.BlockCursor;
import com.facebook.presto.operator.GroupByIdBlock;
import com.facebook.presto.util.array.ObjectBigArray;
import com.google.common.base.Optional;
import io.airlift.slice.Slice;
import static com.facebook.presto.spi.type.VarcharType.VARCHAR;
import static com.google.common.base.Preconditions.checkArgument;
import static com.google.common.base.Preconditions.checkState;
public class VarBinaryMinAggregation
extends SimpleAggregationFunction
{
public static final VarBinaryMinAggregation VAR_BINARY_MIN = new VarBinaryMinAggregation();
public VarBinaryMinAggregation()
{
super(VARCHAR, VARCHAR, VARCHAR);
}
@Override
protected GroupedAccumulator createGroupedAccumulator(Optional<Integer> maskChannel, Optional<Integer> sampleWeightChannel, double confidence, int valueChannel)
{
// Min/max are not effected by distinct, so ignore it.
checkArgument(confidence == 1.0, "min does not support approximate queries");
return new VarBinaryGroupedAccumulator(valueChannel);
}
public static class VarBinaryGroupedAccumulator
extends SimpleGroupedAccumulator
{
private final ObjectBigArray<Slice> minValues;
private long sizeOfValues;
public VarBinaryGroupedAccumulator(int valueChannel)
{
super(valueChannel, VARCHAR, VARCHAR, Optional.<Integer>absent(), Optional.<Integer>absent());
this.minValues = new ObjectBigArray<>();
}
@Override
public long getEstimatedSize()
{
return minValues.sizeOf() + sizeOfValues;
}
@Override
protected void processInput(GroupByIdBlock groupIdsBlock, Block valuesBlock, Optional<Block> maskBlock, Optional<Block> sampleWeightBlock)
{
minValues.ensureCapacity(groupIdsBlock.getGroupCount());
BlockCursor values = valuesBlock.cursor();
for (int position = 0; position < groupIdsBlock.getPositionCount(); position++) {
checkState(values.advanceNextPosition());
// skip null values
if (!values.isNull()) {
long groupId = groupIdsBlock.getGroupId(position);
Slice value = values.getSlice();
Slice currentValue = minValues.get(groupId);
if (currentValue == null || value.compareTo(currentValue) < 0) {
minValues.set(groupId, value);
// update size
if (currentValue != null) {
sizeOfValues -= currentValue.length();
}
sizeOfValues += value.length();
}
}
}
checkState(!values.advanceNextPosition());
}
@Override
public void evaluateFinal(int groupId, BlockBuilder output)
{
Slice value = minValues.get((long) groupId);
if (value == null) {
output.appendNull();
}
else {
output.appendSlice(value);
}
}
}
@Override
protected Accumulator createAccumulator(Optional<Integer> maskChannel, Optional<Integer> sampleWeightChannel, double confidence, int valueChannel)
{
// Min/max are not effected by distinct, so ignore it.
checkArgument(confidence == 1.0, "min does not support approximate queries");
return new VarBinaryMinAccumulator(valueChannel);
}
public static class VarBinaryMinAccumulator
extends SimpleAccumulator
{
private Slice min;
public VarBinaryMinAccumulator(int valueChannel)
{
super(valueChannel, VARCHAR, VARCHAR, Optional.<Integer>absent(), Optional.<Integer>absent());
}
@Override
protected void processInput(Block block, Optional<Block> maskBlock, Optional<Block> sampleWeightBlock)
{
BlockCursor values = block.cursor();
for (int position = 0; position < block.getPositionCount(); position++) {
checkState(values.advanceNextPosition());
if (!values.isNull()) {
min = min(min, values.getSlice());
}
}
}
@Override
public void evaluateFinal(BlockBuilder out)
{
if (min != null) {
out.appendSlice(min);
}
else {
out.appendNull();
}
}
}
private static Slice min(Slice a, Slice b)
{
if (a == null) {
return b;
}
if (b == null) {
return a;
}
return a.compareTo(b) < 0 ? a : b;
}
}